Madeley High School
Mains electricity ED grade questions 60 marks 60 mins
Q1.(a)
Name:_______________________________________
The diagram shows the inside of a three-pin plug.
(i)
What name is given to the wire labelled S?
Draw a ring around the correct answer.
earth
live
neutral
(1)
(ii)
What is the colour of the insulation around the wire labelled T?
Draw a ring around the correct answer.
blue
brown
green and yellow
(1)
(b)
The plug contains a 13 amp fuse.
(i)
Which one of the following is the correct circuit symbol for a fuse?
Draw a ring around the correct answer.
(1)
(ii)
The diagram shows the parts of the fuse.
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What would happen if a current of 20 amps passed through the 13 amp fuse?
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(1)
(c)
(i)
Not all electrical appliances are earthed.
Which one of the following appliances must be earthed?
Tick ( ) one box.
Table lamp
Toaster
Hair
straightener
s
Give a reason for your answer.
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(2)
(ii)
Earthing an appliance helps to protect a person against a possible risk.
What is the risk?
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(1)
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(d)
The diagrams show how two lengths of mains electrical cable were joined. The
individual wires have been twisted together and covered with insulating tape. This is
not a safe way to join the cables.
What is the possible risk from joining the two lengths of mains electrical cable in this
way?
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(1)
(e)
The diagram below shows a connecting box being used to join two lengths of
electrical cable. This is a safe way to join the cables.
The cable grips are important parts of the connecting box.
Explain why.
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(2)
(Total 10 marks)
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Q2.The diagrams show oscilloscope traces. Three different alternating current (a.c.) electricity
supplies, J, K and L, produce these traces.
In each diagram, one vertical division on the oscilloscope screen represents 2 volts.
(a)
Which one of the electricity supplies, J, K or L, has the largest peak potential
difference?
Write your answer, J, K or L, in the box.
(1)
(b)
Calculate the value of the largest peak potential difference.
........................................................................................................................
Largest peak potential difference = ................................... V
(1)
(c)
The oscilloscope is now connected across a 3 V battery. The battery supplies direct
current (d.c.). The settings on the oscilloscope are not changed.
On the diagram below draw the trace you would see on the oscilloscope screen.
(2)
(Total 4 marks)
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Q3.
The diagrams show the inside of a 13 amp plug.
(a)
(i)
Which one of the plugs, A, B, C or D, is correctly wired?
Write your answer, A, B, C or D, in the box.
A
B
C
D
The plug that is correctly wired is
(1)
(ii)
What material is the outside casing of a plug made from?
...............................................................................................................
(1)
(b)
An electric drill draws a current of 2 amps from the 230 volt mains electricity supply.
Use the equation in the box to calculate the power of the drill.
power
=
current
×
potential difference
Show clearly how you work out your answer.
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Power .................................................. watts
(2)
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(c) A householder needs to replace a damaged plug. Most replacement plugs are sold with a 13
amp fuse fitted inside. The householder thinks it would be better for shops to sell the plugs without a
fuse. He could then buy either a 3 A, 5 A or 13 A fuse to fit inside the plug.
Explain an advantage of selling plugs without a fuse, rather than with a 13 amp fuse
fitted.
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(2)
(Total 6 marks)
Q4.(a)
The diagram shows the information plate on an electric kettle. The kettle is plugged into the
a.c. mains electricity supply.
230 V
2760 W
50 Hz
Use the information from the plate to answer the following questions.
(i)
What is the frequency of the a.c. mains electricity supply?
...............................................................................................................
(1)
(ii)
What is the power of the electric kettle?
...............................................................................................................
(1)
(b) To boil the water in the kettle, 2400 coulombs of charge pass through the heating element in
200 seconds.
Calculate the current flowing through the heating element and give the unit.
Use the correct equation from the Physics Equations Sheet.
Choose the unit from the list below.
amps
volts
watts
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Current = ............................................................
(3)
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(c)
The amount of charge passing through the heating element of an electric kettle
depends on the time the kettle is switched on.
What pattern links the amount of charge passing through the heating element and
the time the kettle is switched on?
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(2)
(Total 7 marks)
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Q5.
(a)
The diagram below shows the three pins in a mains plug. The pins connect with
the live, neutral and earth terminals in a socket.
On the diagram, label each pin to show which is:
the live pin,
the neutral pin,
the earth pin.
(3)
(b)
The diagram below shows the inside of a mains plug.
(i)
Name one material which could be used for the part labelled X.
..........................................................................................................................
(ii)
Complete the sentences below.
The part labelled Y is called the ................................................................... .
This is used to hold the ........................................................ firmly in place.
The component labelled Z is the .................................................................. .
(iii)
The plug is used with an electric fire.
Which part of the electric fire is connected to the earth pin?
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(5)
(Total 8 marks)
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Q6.
The diagram shows the inside of a mains plug.
(a)
Complete the table.
Wire
Colour of insulation
Earth
Live
Neutral
(3)
(b)
The diagram shows a washing machine without an earth connection. The live wire
has become loose and is touching the metal case of the washing machine.
(i)
Draw on the diagram the path taken by the electricity when the person touches
the metal case of the machine.
(1)
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(ii)
Describe how the path of the electricity would change if the washing machine
had an earth connection.
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(2)
(c)
Some electrical appliances use a cable which does not have an earth wire. Which
one of the following appliances can safely use this type of cable?
hairdrier
iron
refrigerator
..................................................................................................................................
Give a reason for your answer.
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(2)
(Total 8 marks)
Q7.(a)
The diagram shows the inside of an incorrectly wired three-pin plug.
(i)
What two changes need to be made so that the plug is wired correctly?
1 ............................................................................................................
...............................................................................................................
2 ............................................................................................................
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(2)
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(ii)
The fuse inside a plug is a safety device.
Explain what happens when too much current passes through a fuse.
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(2)
(b)
Each of these pictures shows an electrical appliance being used in a bathroom.
Using the hairdryer in picture A is dangerous. However, it is safe to use the batteryoperated radio in picture B. Explain why.
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(2)
(Total 6 marks)
Q8.
(b) A householder does not have enough electric sockets in the
kitchen. To overcome the problem, the householder uses two
adaptors to plug five appliances into a single electric socket.
Explain why this is dangerous.
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(2)
(Total2 marks)
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Q9.
(i)
(a)
The diagram shows a piece of two-core cable and a piece of three-core cable.
Which one of the wires inside a three-core cable is missing from a two-core cable?
Draw a ring around your answer.
earth wire
live wire
neutral wire
(1)
(ii)
Use a word from the box to complete the following sentence.
double
extra
totally
A pottery table lamp fitted with a two-core cable is safe to use because it is
................................................. insulated.
(b)
(1)
The cables connecting the power sockets in a building contain wires 1.8 mm thick.
The maximum current that can safely pass through these wires is 20 amps. A fuse is
included in the circuit to protect the wiring.
Explain how a fuse protects the wiring of a circuit.
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(3)
(Total 5 marks)
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M1.(a)
(i)
(ii)
brown
(b)
(i)
neutral
1
1
centre symbol ringed
accept any correct indication
(ii)
fuse (wire) melts
accept fuse blows
accept fuse breaks / snaps
accept burns out appliance doesn’t work is insufficient
overheat is insufficient
do not accept blows up
(c)
(i)
1
Toaster
1
(only one with) a metal case / outside
reason only scores if toaster chosen
accept it is metal
accept outside / case / metal conducts (electricity)
do not accept it conducts electricity
(ii)
electric shock / electrocution
do not accept explosion
(d)
1
1
overheating of cables or fire
it refers to the electric cable
accept short circuit / sparking
overheating of tape is insufficient
do not accept electrocution / shock
1
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(e)
stop cable(s) being pulled loose / free
accept wire(s) for cable(s)
accept to hold cables in place
1
and so breaking the circuit or and shorting (one wire to another)or and causing a fire risk / sparking
accept appliance / plug would not work
1
[10]
M2.(a) L
1
(b)
6 (V)
1
(c)
horizontal line drawn
drawn in correct position
1
judge by eye
1
[4]
M3.
(ii)
(a)
(i)
D
1
plastic or rubber
accept a specific type of plastic
accept electrical insulator
1
(b)
460
allow 1 mark for correct substitution ie 2 × 230
(c)
any two from:
•
not all appliances need a 13 A fuse
2
idea that 13 A is (much) bigger than required by many appliances
do not accept some appliances require more than 13 A
do not accept 13 A fuse will blow
•
can choose the most suitable fuse (for the appliance)
accept install correct fuse for the appliance
•
(in the event of a fault) 13 A fuse may allow too much current to flow through an appliance
or
fuse may not melt (before appliance is damaged)
•
may already have the fuse
idea of reusing a fuse
do not accept cheaper unless explained correctly
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M4.(a)
b)
(i)
50 (Hz)
(ii)
1
2760 (W)
1
12
allow 1 mark for correct substitution, ie 2400/200
or
allow 1 mark for 2760/230 provided no subsequent step shown
amps
(c)
2
1
the charge is directly proportional to the time switched on for
accept for 1 mark the longer time (to boil), the greater amount of charge
or positive correlation
or they are proportional
M5
(b)
(a)
(i)
Earth
[7]
2
neutral
live
rubber/plastic
for 1 mark each
for 1 mark
3
1
(ii) cable/wire/grip
cable/wires
fuse
for 1 mark each
(iii)
M6.
live
case
(a)
3
for 1 mark
earth
[8]
1
yellow and green
accept green and yellow
1
brown 1
neutral blue 1
(b) (i) path shows electricity flowing from washing machine through to
the person (and on to earth)
ignore direction of arrows
1
(ii) electricity flows through earth wire
(to earth) or goes to ground
not escaping electricity
not fuse wire blowing
1
not through the person or miss the person or not electrocuting
not electric shock
1
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(c)
hairdrier
hairdrier needed for second mark except allow double insulated if iron or fridge but not plastic case
1
double insulated or plastic case
accept ‘It’s made of plastic’
accept ‘it does not conduct’
M7.(a)
(i)
[8]
1
connect the earth wire (to pin)
answers must be in terms of correcting the faults
1
screw cable grip (across cable)
accept tighten the cable grip
(ii)
•
1
any two from:
fuse gets (very) hot•
fuse melts
accept blows for melts
do not accept break / snap fuse / blow up
•
circuit breaks / switches off
accept stops current flowing
2
(b)
any two from:
•
hairdryer is plugged into mains (electricity socket)
it refers to hairdryer
hairdryer works from the mains
orhairdryer is using 230 V
accept 240 for 230
•
water conducts electricity
do not accept water and electricity don’t mix
•
radio is low power / current / pd / voltage
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accept radio not connected to the mains
do not accept radio is waterproof
•
(the current in / pd across) hairdryer more likely to give a (fatal) electric shock
accept the idea of electrocution if hairdryer is wet
accept the idea of radio not causing electrocution if wet
2
[6]
M8.
(b)
any two from:
•
draws too high a current
accept power for current
do not accept electricity/ electric for current
accept too much current goes through the socket
do not accept too many currents go through the socket
•
socket overloaded
it = socket do not accept circuit for socket
•
wiring gets too hot / melts
accept socket for wiring
do not accept fuse melts or blows
do not accept plug/ appliances overheating
•
(may) cause a fire
•
(may) cause sparking
•
(possible) physical damage to the socket
a physical reason, such as stick out from the wall is insufficient
ignore reference to electric shocks
2
[6]
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M9.
(a)
(i)
earth wire
1
(ii)
double
1
(b)
if too much current flows through the wire
accept power for current
do not accept electricity for current
accept if more than 20 amps flows through the wire
1
the fuse (overheats and) melts
accept ‘blows’ for melts
do not accept explodes / breaks / snaps etc
1
breaking the circuit
accept stopping the current flow
1
[5]
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